Lethal Alleles and Their Effects

In this video, Professor Thiago Ferreira discusses the concept of lethal alleles, which can cause death in organisms either during embryonic development or after birth. The video explains how these alleles can be dominant or recessive and how they affect Mendelian ratios. Two case studies are presented: one involving mouse coat color and another on human achondroplasia. The video concludes with a call to action for viewers to engage with the channel.

What is the main topic of the video tutorial?

• Photosynthesis

• Cell Division

• Human Anatomy

• Mendel's First Law and its variations

What are lethal alleles?

• Alleles that cause death in the embryonic stage or at birth

• Alleles that enhance survival

• Alleles that only affect plant species

• Alleles that have no effect on the organism

How do lethal alleles affect Mendelian ratios?

• They do not affect Mendelian ratios

• They cause a 1:1 ratio

• They cause a 4:1 ratio

• They alter the classic 3:1 phenotypic ratio

What is a characteristic of a lethal dominant allele?

• It is only lethal in homozygous form

• It is always beneficial

• It is lethal in heterozygous form

• It has no effect on the organism

In the case of coat color in mice, what happens when the dominant allele is in homozygous form?

• The mice are unaffected

• The mice do not survive

• The mice have enhanced survival

• The mice are born with a different color

What is the phenotypic ratio observed in the coat color of mice due to lethal alleles?

• 3:1

• 1:1

• 4:1

• 2:1

What genetic condition in humans is used as an example of lethal alleles?

• Huntington's disease

• Achondroplasia

• Cystic fibrosis

• Sickle cell anemia

What is the phenotypic ratio observed in achondroplasia due to lethal alleles?

• 4:1

• 2:1

• 3:1

• 1:1

Why are there no documented cases of homozygous dominant individuals with achondroplasia?

• They do not survive to adulthood

• They are unaffected

• They are always healthy

• They have a different condition

What should you consider when solving exercises involving lethal alleles?

• The 4:1 ratio

• The classic 3:1 ratio

• The altered 2:1 ratio

• The 1:1 ratio